Rod knock/piston slap...coming from the clutch?

Cars in neutral. Idling. Randomly starts making very minor piston slap/rod knock noise.

I cry, pray to Chesty, then push the clutch in to take off from the light cause idgaf. As soon as I push the clutch in, bam, no more noise. I let it out..noise.

Wtf? Never heard a ****ing clutch make these types of noises....

Oh ****. I think I got that backwards..

Fml do I actually have to build my bottom end -_-

If it helps, when I push the clutch in and give it a slight rev, no noise from the bottom end. Also, when I hear this sound in neutral and rev it high, engine purs like a sexy kitten.

The trans has been feeling very notchy, and overall drives like ****. Might be running the original fluid. What I think I'm hearing is something in the tranny? I mean, even in neutral the engine is still spinning the tranny. I put the clutch in, rotating mass in tranny stops, therefor sound stops. Right??

You might have a lightweight flyhweel which exhibits "chatter" at idle speed. Its not a cause for concern unless the issue appeared out of nowhere.

Changing your transmission fluid would be a good first step.

thee antic....
how big are your rims? and what style front lights do you have?

Just talked to the PO, stock flywheel. Sachs clutch.

Just bought the car.

Stock headlights, clear corners, 18 or 19" ASA rims. I'll check tonight.

one item to check is the starter as well. in my 318 the starter wouldn't retract all the way causing the noise you describe. Replacing that solved my problem.

As for the clutch chatter, my current 328 only does that when engaged and moving with very low revs. Say in reverse up a hill where RPM's are less than 900...
If you are having clutch chatter, then that would mean your clutch is not disengaging all the way.

I would also check for a CEL. Make sure it works (key on, engine off, all lights should come on for a moment).

If you can, post a video/sound clip of the noise.

I will get on that tonight, so you don't think it's the bottom end then?

I don't know, it very well could be. its better to check and research first before tearing apart and throwing money away

Originally Posted by Thee_Antic

I will get on that tonight, so you don't think it's the bottom end then?

I highly doubt its the lower end. If it goes, it would make noises so horrible it would be undriveable.

is it possible someone machined the flywheel?

I think i read somewhere you arent supposed to do that on our cars

Originally Posted by Dino1394

is it possible someone machined the flywheel?

I think i read somewhere you arent supposed to do that on our cars

After YEARS of believing the same thing was finally clarified to me. Most shops & machinists aren't capable of it, but resurfacing dual mass flywheels IS possible.

As soon as I push the clutch in, bam, no more noise. I let it out..noise.

transmission low on oil or worn out mainshaft bearing. Top it off with 30w non detergent oil, noise should go away.

Turned out it was indeed low/bad trans fluid. Switched it out and voila, no more noise.

I assume you used lubricant appropriate to the gearbox.

(FYI, 30w non-detergent isn't)

Originally Posted by Thee_Antic

Turned out it was indeed low/bad trans fluid. Switched it out and voila, no more noise.

You did not even say "thanks", next time don't be stupid and check the obvious fluid levels before wasting everybodies time here.

Are you ****ing kidding me?

Originally Posted by HakenTT

You did not even say "thanks"

^Well that was odd... Maybe now would be a good time to pull those panties from your crack? In reality, we should be angry with you for recommending that someone put 30W oil in their transmission...

Hmm. Had some quality seat time with the car today, and noticed that the sound did indeed come back. I parked her, got on my back with my trusty stethoscope and listened away. Sound is gear noise from the trans..definitely. Engine sounds normal. Can hear the crank and rods, pretty smooth. The trans however, sounds like this:



Regardless..I"m just going to swap it out anyways. It definitely shifts better with the new fluid, no more grinds or notchiness.

Originally Posted by Thee_Antic

Hmm. Had some quality seat time with the car today, and noticed that the sound did indeed come back. I parked her, got on my back with my trusty stethoscope and listened away. Sound is gear noise from the trans..definitely. Engine sounds normal. Can hear the crank and rods, pretty smooth. The trans however, sounds
Regardless..I"m just going to swap it out anyways. It definitely shifts better with the new fluid, no more grinds or notchiness.

Once the tranny is run low on ATF oil for long time, then few bearings inside may wear out and make noise. This is why I said to top it off with non detergent 30W oil, it will delute just fine with ATF and will ticken the viscosity just enough to quiet down the bearings. At least I saved you from engine rebuilding

we should be angry with you for recommending that someone put 30W oil in their transmission...

No, ZeGerman we should all be angry at you for not recommending anything.

Sounds like the transmission input shaft bearing. Common on e30s, not sure about e36s. If it is the input shaft bearing then it wont cause damage or fall apart, just be annoying. Changing fluid usually doesnt help.

A) There was the proper amount of fluid in the trans when I changed it out, it was never low, just old. Clearly the thing has been used and abused, case closed.

B)Detergent anything, no.

C)Don't talk **** to Mr.German. If he has no knowledge on the subject I would much rather him not butt in with detrimental advice, like telling me to put 30w detergent oil in my trans.

B)Kindly, gtfo.

Originally Posted by Victell

Sounds like the transmission input shaft bearing.

I thought about this..didn't think the noise would be this..bad?

Irregardless. Its getting switched out sooner than later, so no worrys

(They should arrive in the mail tmrw)

i wanna know how adding non detergent w30 to a trans saved him from rebuilding his engine...




df

That guy is nothing but a troublemaker. One look at his youtube videos and his posts on other auto forums pretty much confirms his status as a jerk.